The Crow Reservation community is exposed to high concentrations of environmental contaminants through a number of factors. These include: 1) widespread leasing of agricultural lands, which may reduce the incentive for operator environmental stewardship; 2) the lack of regulations on reservation lands to mitigate environmental effects of agriculture; 3) subsistence hunting and gathering and other traditional practices that increase exposure risk to environmental contaminants; 4) inadequate/outdated or non-existent water and wastewater treatment systems; and 5) the unequal distribution of mine and other toxic waste sites on Reservation lands. This proposal describes a Community Based Participatory Research (CBPR) collaboration between Environmental Health faculty from Montana State University; the Crow Tribe's environmental, health, natural resources and agriculture directors; health and civil engineering professionals from the Indian Health Service Hospital in Crow Agency; science faculty from Little Big Horn College (LBHC) on the Crow Reservation; Big Horn County Commissioners and additional organizations and community members from the Crow Tribe. The major objective of this research is to build on an existing partnership between the University and the Crow community, including LBHC, to address environmental health hazards on the Crow Reservation, particularly in relation to the high rates of cancer in the Crow tribe and the anecdotal evidence from community members of cancer clusters that are believed to be related to poor quality water and other environmental exposures. The community will participate in every phase of the work which will involve, 1) Establishing a sampling and analysis program to adequately assess contaminant loadings to drinking waters and subsistence foods; 2) Evaluating exposure pathways and subsistence and other cultural practices that contribute to exposure risk; 3) Communicating risks to community residents and developing and providing recommendations for exposure mitigation and future monitoring.